(a) Run-off basis means that the liability of the reinsurer under policies, which became effective under the treaty prior to the cancellation date of such treaty, shall continue until the expiration date of each policy;
(b) Cut-off basis means that the liability of the reinsurer under policies, which became effective under the treaty prior to the cancellation date of such treaty, shall cease with respect to losses resulting from accidents taking place on and after said cancellation date.
Usually the reinsurer will return to the company the unearned premium portfolio, unless the treaty is written on an earned premium basis.